How long you think SensorTag 2 will last on single 3V coin battery?
During my first SensorTag2 review video I had issue with that no all sensors were working properly, I was wondering if I got defective unit, turned out that battery which SensorTag 2 was shipped with was pretty low on juice. And the battery was just out of the box, so I assume it would just work perfectly. After installing perfectly fresh battery SensorTag 2 start working with no issue, this prompted be to investigate power consumption of SensorTag 2.
I also created video explaining what I did and how I measured current during SensorTag2 operation, please watch it here:
I tired to measure current in different modes like: discovery, connecting, powering on, all sensors on and full sample rate, only some sensors working etc in order to figure out how long SensorTag will work on 3V coin battery.
Here is the table showing compiled result of my analysts:
Powering On: 12mA
Discovery ( LED Blinks ): 0.4mA / 2mA ( LED current)
All Sensors Off: 0.44mA
All Sensors ON at maximum data rate (100ms sample rate) ~5.5mA
Just Temperature Sensor (Ambiet + IR): 0.84mA
Just (Ambiet + IR + Humidity Sensors): 0.92mA
Just Light Sensor slow / fast sample rate: 0.56mA / 0.68mA
Just Motion Sensor Sensor slow / fast sample rate: 4.16mA / 4.68mA
Just Barometric Sensor: 0.5mA
Standard CR2032 coin battery has typical capacity 240mAh, so we cannot expect SensorTag 2 work longer then 48 hours in maximum mode – when all sensors are powered on and at maximum sample rate, and about 240 hours when just few sensors working for example temperature and humidity. Curious what TI guys meant they said it suppose to work for 1 year on single battery, will need to do more investigation, may be it needs firmware update, or it just power consumption of CC2650 alone? I don’t really know….
Potential alternative would be running SensorTag 2 from 1cell LiPo, but this will require very efficient 3.7V -> 3V DC-DC converter, this may not be trivial task as I haven’t seen any off the shelve units like this.